Shotgun choke



April 1966 B. WEISER 3,243,910

SHOTGUN CHOKE Filed Feb. 2, 1965 F/G 2 52 7 f 3 I I 6 /6 2% 20 J INVENTOR. BERNARD WEISER ATTORNEYS United States Patent 3,243,910 SHOTGUN CHOKE Bernard Weiser, 51 Canal St., Weatogue, Conn. Filed Feb. 2, 1965, Ser. No. 429,720 14 Claims. (Cl. 42-79) This invention relates to improvements in shotgun choke attachments and has for its general object the provision of an improved adjustable choke for elfectively controlling a shotgun shot pellet pattern.

Another object of the invention is to provide an adjustable shotgun choke which may be rapidly and accurately selectively conditioned to effect a desired shot pellet distribution.

A further object of the invention is to provide a shotgun choke which reduces the recoil and muzzle blast of a shotgun.

A still further object of the invention is to provide an adjustable shotgun choke of simple and yet durable design and construction and which may be manufactured at low cost.

The drawing shows preferred embodiments of the invention and such embodiments will be described, but it will be understood that various changes may be made from the constructions disclosed, and that the drawing and description are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

In the drawing:

FIG. 1 is a plan view of a shotgun choke embodying the present invention.

FIG. 2 is a longitudinal section, taken generally along the line 2-2 of FIG. 1, showing the device mounted on the muzzle end of a shotgun barrel.

FIG. 3 is a transverse section taken generally along the line 33 in FIG. 2.

FIG. 4 is a partially sectional side elevation of a modified form of the choke shown in FIG. 1.

Referring now to the drawing, and particularly to FIGS. 1 and 2, a choke embodying the present invention is indicated generally by the reference numeral 10. The choke generally comprises a tubular shell 12 having a central bore 14 adapted to receive a shotgun muzzle 16 and a collar 21). At least one vent opening 18, 18 communicates with the central bore 14 for venting the gases of explosion when the gun is discharged. A closing means 20 is provided for closing at least a portion of the vent opening. In the presently preferred form of the invention three vent openings 18, 13 are employed. The vent closing means is preferably a collar 20 surrounding a substantially smooth portion 24 of the shell 12, slidably mounted thereon for adjustable positioning therealong. The collar 20 may be positioned to expose all of the vents 18, 18 or to cover or ciose one or two of them; however, it should be noted that in the presently preferred embodiment of the invention at least one vent remains open or uncovered at all times. A means for selectively positioning the collar 20 relative to the shell 12 is provided by a ball detent mechanism indicated generally by the numeral 22.

The shell 12 is preferably cylindrical having a smooth surface portion 24 and a forward or muzzle end portion 26 of reduced diameter to aid in heat dissipation. The surface of the muzzle end portion is preferably knurled to facilitate handling the device and to improve its general appearance. A plurality of radially contoured annular grooves 28, 28 are defined in the muzzle end portion 26. One of these grooves serves as a receptacle for a ball detent mechanism associated with a dispersion adapter to be described hereinafter. The remaining grooves 28,

28 merely enhance the appearance of the device.

The central bore 14 extends coaxially through the shell 12 and includes a first cylindrical bore portion 30 adapted to receive the shotgun muzzle 16 in press fit relationship. The choke 10 may be permanently secured to the gun muzzle by an appropriate metal fusion process, such as silver soldering. It should be noted that when the choke attachment is positioned upon the shotgun it extends forwardly from the gun muzzle in coaxial alignment with the gun bore.

Since it may be necessary to remove the forward sight from the shotgun in order to attach the choke to the gun, a sighting means is preferably provided on the choke. In one presently preferred embodiment of the invention the sighting means is a bead sight 32 threadably secured to the collar 20; however, it should be apparent that the type of sight used and its location upon the choke may be varied to suit the markmans preference.

The central bore 14 also includes a second portion 34 adjacent the muzzle 16 and a cylindrical third or forward portion 36 adjacent the portion 34. The portion 34 is tapered to converge from the muzzle to the cylindrical portion 36. It should be further noted that the tapered second portion has a major diameter at least equal to the diameter of the shotgun bore, whereas the cylindrical third portion 36 has a diameter smaller than the diameter of the gun bore.

The vent openings 18, 18 defined within the shell 12 are preferably longitudinally aligned transversely extending slots which communicate with the cylindrical third or forward portion 36. In the present preferred embodiment of the invention, the openings 18, 18 are obliquely disposed to the central bore axis for forwardly exhausting the gases of explosion, and are all located to one side of an axial plane of the bore for a purpose to be further discussed hereinafter.

A pair of diametrically opposed transversely aligned apertures 19, 19 defined by the shell 12 also communicate with the cylindrical third portion 36.

Three slot-shaped vent openings 18, 18 are shown in the embodiment of the invention here described; however, it will be apparent from the description which follows that the number, shape and size of these openings may vary without departure from the spirit of the invention.

The collar 21) is preferably an annular ring surrounding the smooth portion 24 in slidable engagement therewith adapted for axial movement therealong and selective positioning relative thereto.

A ball detent mechanism, indicated generally by the numeral 22, provides means for retaining the collar 20 in selected longitudinal position relative to the shell 12. A ball 38 positioned within a radial aperture 40 in the collar 29 is urged radially inwardly by an annular spring 42 positioned within an annular recess 44 in the collar 26. The recess 44 is radially aligned with the aperture 40. A longitudinal recess 46, defined in the outer surface of the shell 12, is adapted to receive a portion of the ball 38 therein, limiting the overall longitudinal travel of the collar 20 relative to the shell 12 and serving to prevent rotational movement of the collar relative to the shell. Sockets 48, 48 associated with the recess 46 are adapted to receive a portion of the ball 38 thereby providing means for retaining the collar 2% in selected longitudinal position relative to the shell 12.

In the choke of FIGS. 1 through 3, the collar 20 may be selectively positioned in any one of three positions. In the open choke or full line position of FIG. 2, the collar 20 resides in a maximum rearward position toward the gun muzzle exposing all three of the vent openings 18, 18 to allow for maximum venting of the gases. In the full choke or broken line position of FIG. 2, the collar 20 achieves maximum forward position and covers two of the three vent openings 18, 18. It should be noted that the forwardmost vent 18 remains uncovered at all times, thereby allowing some gas to be vented from the bore 14 when the collar is in the full choke position. An intermediate collar position shown in FIG. 1, is also provided wherein only one of the three vent openings 18, 18 is covered.

The gases of explosion expand in all directions as they emerge from a shotgun muzzle. Since the shot column in a shotgun shell comprises a multiplicity of individual pellets, it does not respond as a mass when it is propelled by the expanding gas. The laterally expanding gases tend to impart lateral velocity to the pellets in the outer layers of the shot column as they leave the muzzle resulting in lateral dispersion of some of the pellets with a resulting loss of shot pattern density. This problem is well known to those skilled in the shotgun art.

In the choke of the present invention, the shot column leaves the muzzle of the shotgun and enters the choke through a tapered bore section from which it passes into the cylindrical bore section 36 having a bore smaller than the shotgun bore. Thus, the shot column is somewhat compressed and its density is increased under the maximum available pressure of the expanding gases. The cylindrical bore section 36 tends to direct the compacted shot column on a substantially true flight to its mark. Increasing the density of the shot column before it leaves the forward end or muzzle of the choke is believed to reduce the influence of the laterally expanding gases upon it. It will also be noted that provision is made to vent some of the expanding gases of explosion from the choke bore after the shot column has entered the cylindrical portion or section 36 of the bore. The selectively positioned collar 20 provides means for controlling the escape of gas through the vent openings communicating with the central bore of the choke thereby controlling the amount of expanding gas which ultimately emerges at the choke muzzle. Shotgun shells are available in a wide variety of charge weights, shot sizes and shot counts. The adjustable feature of the choke of the present invention enables the marksman to adapt his shotgun to employ the characteristics of a given shell most elfectively.

As previously noted, all of the vent openings 18, 18 lie on one side of an axial plane of the shell 12. The choke of the present invention is normally mounted on the shotgun with the vent openings facing upwardly; therefore, the gases of explosion escaping from these vents exert a downward thrust at the muzzle end of the gun. In the normal shooting position, one of the marksmans hands is placed upon the underside of the gun forestock, thereby supporting the forward portion of the gun and providing a natural resistance to downward thrust. Thus, it should be apparent that the escaping gases exert a force in a direction opposite to the balancing force exerted by the marksman in holding the gun. Since the marksman is prepared to compensate for this downward thrust and can readily do so, he is able to retain more effective control of the gun at the instant of discharge, thereby reducing muzzle movement and the further shot pattern disturbance which otherwise might result therefrom.

In a large gauge shotgun, such as a twelve gauge, a relatively heavy powder charge is used and it has been found that under some shooting conditions, better control may be effected by discharging some of the gases of explosion transversely of the gun barrel. It is for this reason that the diametrically opposed transverse apertures 19, 19 are provided. It should be noted that in the open choke position, the collar 2%) assumes a maximum rearward position exposing the apertures 19, 19 whereas, these apertures are partially covered by the collar in the intermediate collar position and fully covered in the full choke or maximum forward position. Such transverse apertures are preferably not provided on chokes for smaller gauge shotguns.

Referring now to FIG. 4, wherein a modified form of choke of FIG. 1 is indicated generally at a, it will be noted that a cylindrical shell 12a includes a central bore 14a. having a cylindrical bore portion 36a and other bore characteristics identical to those of the aforedescribed choke.

The cylinder 12a defines a plurality of vent openings 18a, 13a communicating with a central bore which openings are in all respects similar to those of the choke of FIG. 1. An internally threaded collar 20a cooperates with an externally threaded portion 24a of the shell 12a, thereby providing means for selectively positioning the collar along the shell. Also included upon the shell 12a is at least one annular flange 13, 13 having a surface 15, 15 normal to the shell axis and forwardly adjacent at least one of the vent openings 18a, 18a.

The vent openings are so disposed relative to the associated flange surfaces 15, 15 that the gases escaping from a vent impinge upon an associated surface to impart a forward thrust thereto. This arrangement renders the choke recoil responsive. It should also be noted that the lateral escape of gas from the vent opening 1811 not associated with a flange surface 15 also serves to materially reduce recoil.

A sighting means 32a is mounted on one of the annular rings 13, 13 in the modified choke shown in FIG. 4.

A further modification of a shot pattern may be elfected by the use of a dispersion adapter indicated generally by the numeral 42 as shown in FIG. 4. The adapter 42 comprises a tubular section 44 having a cylindrical bore portion 46 adapted to engage a muzzle end portion 26a of the tubular shell 12a.

Means for releasably retaining the section 44 in engagement with the shell 12a is provided by a ball detent mechanism 22a generally similar to the aforedescribed ball detent mechanism 22. One of the annular radially contoured recesses 28a, 28a on the muzzle end portion 26a provides a receptacle for the ball detent mechanism 22a.

The adapter 42 includes a tapered bore section 50 adjacent and coaxially aligned with the third or cylindrical portion 36a. The tapered bore portion 50 has a diameter adjacent the third portion at least equal to the diameter of the third portion 36a. The tapered section 50 may either converge or diverge from the third portion in accordance with the shot pattern modification desired. An adapter 42 having a diverging bore 50 is shown in full lines in FIG. 4. A converging bore 50 shown in the same figure is indicated by broken lines.

The invention claimed is:

1. A choke attachment for a shotgun comprising a tubular shell having a central bore, said bore including a first portion adapted to receive the muzzle of a shotgun and extend forwardly therefrom in coaxial alignment therewith, said bore including a second portion adjacent said first portion, said bore further including a generally cylindrical third portion adjacent said second portion, said third portion having a diameter smaller than the shotgun bore diameter, said shell defining at least one vent opening communicating laterally with said third portion, and means for selectively closing at least a portion of said vent opening.

2. A choke attachment for a shotgun comprising a tubular shell having a central bore, said bore including a first portion adapted to receive the muzzle of a shotgun and extend forwardly therefrom in coaxial alignment therewith, said bore including a second portion adjacent said first portion, said bore further including a generally cylindrical third portion adjacent said second portion, said third portion having a diameter smaller than the shotgun bore diameter, said shell defining a plurality of vent openings communicating laterally with said third portion, and means for selectively closing at least one of said vent openings.

3. In a choke attachment for a shotgun the combination comprising a tubular shell having a central bore, said bore including a first portion adapted to receive the muzzle of a shotgun and extend forwardly therefrom in coaxial alignment therewith, said central bore including a second portion adjacent said first portion, said central bore further including a generally cylindrical third portion adjacent said second portion, said third portion having a diameter smaller than the shotgun bore diameter, said shell defining a plurality of vent openings communicating with said third portion, a collar surrounding a peripheral portion of said shell, and means for selectively positioning said collar relative to said shell to cover at least one of said vent openings.

4. In a choke attachment for a shotgun muzzle, the combination comprising a tubular shell having a central bore, said shell being adapted to receive the muzzle of a shotgun and extend forwardly therefrom in coaxial alignment therewith, said central bore including a cylindrical bore portion having a diameter smaller than the shotgun bore diameter, said central bore further including a tapered bore portion intermediate said cylindrical bore portion and the muzzle converging to said cylindrical bore portion, said tapered bore portion having a major diameter at least equal to the diameter of the shotgun bore, said shell defining a plurality of vent openings communicating with said cylindrical bore portion, a collar adapted to surround a peripheral portion of said shell and means for selectively positioning said collar relative to said shell to cover at least one of said vent openings.

5. The combination as defined in claim 1 further characterized by the addition of sighting means.

6. The combination defined in claim 1 further characterized by an additional tubular section adapted to engage the forwardly extending end portion of said tubular shell, said section defining a tapered bore adjacent said third portion coaxial therewith, said tapered bore having a diameter adjacent said third portion at least equal to the diameter of said third portion and means for releasably retaining said section in engagement with said shell.

7. The combination set forth in claim 6 wherein the means for releasably retaining said section is a ball detent mechanism.

8. The combination as set forth in claim 2 wherein said vent openings are disposed on one side of an axial plane of said shell.

9. The combination defined in claim 2 further characterized by said shell including at least one flange surface thereon normal to the axis thereof forwardly adjacent at least one vent opening, said vent openings being so disposed that gases escaping therefrom impinge upon said flange surface.

10. The combination as set forth in claim 3 wherein said means for selectively positioning said collar is a ball detent mechanism.

11. The combination set forth in claim 3 wherein said means for selectively positioning said collar is provided by said shell having an externally threaded portion and said collar having internal threads cooperating with said externally threaded portion for selectively positioning said collar therealong.

12. A choke attachment for a shotgun comprising a cylindrical shell having a coaxial central bore, said bore including a first portion adapted to receive the muzzle of a shotgun and extend forwardly therefrom in coaxial alignment therewith, said bore including a tapered second portion adjacent said first portion, said bore further including a cylindrical third portion having a diameter smaller than the diameter of the shotgun bore, said second portion converging to said cylindrical portion, said second portion having a major diameter at least equal to the shotgun bore diameter, said shell defining a plurality of longitudinally spaced apart transversely extending slots communicating with said third portion, said slots being disposed on one side of an axial plane, and being obliquely disposed to said axis to forwardly exhaust the gases of explosion, an annular collar encircling a portion of said shell, and means for selectively positioning said collar relative to said shell to cover at least one of the said slots.

13. A choke attachment for a shotgun comprising a tubular shell having a central bore, said bore including a first portion adapted to receive the muzzle of a shotgun and extend forwardly therefrom in coaxial alignment therewith, said bore including a second portion adjacent said first portion, said bore further including a generally cylindrical third portion adjacent said second portion, said third portion having a diameter smaller than the shotgun bore diameter, said shell defining at least one vent opening, communicating laterally with said third portion, said vent opening being located in a half section of said third portion adjacent said second portion, and means for selectively closing at least a portion of said vent opening.

14. A choke attachment for a shotgun comprising a tubular shell having a central bore, sa-id bore including a first portion adapted to receive the muzzle of a shotgun and extend forwardly therefrom in coaxial alignment therewith, said bore including a second portion adjacent said first portion, said bore further including a generally cylindrical third portion adjacent said second portion, said third portion having a diameter smaller than the shotgun bore diameter, said shell defining at least one vent opening, communicating laterally with said third portion, and means for selectively closing only a portion of said vent opening.

References Cited by the Examiner UNITED STATES PATENTS 2,191,484 2/1940 Hughes 8914.3 2,306,176 12/1942 Mathis 4279 2,322,370 6 1943 Lance 8914.3 2,453,121 11/1948 Cutts 4279 X 2,484,988 10/1949 Finlay 4279 2,484,998 10/1949 Hutchinson 4279 2,629,958 3/1953 Roper et al. 4279 2,796,005 6/ 1957 Shapel 8914.3 2,989,815 6/1961 Hare 4279 3,161,979 12/1964 Lowe 4279 BENJAMIN A. BORCHELT, Primary Examiner. 

1. A CHOKE ATTACHMENT FOR A SHOTGUN COMPRISING A TUBULAR SHELL HAVING A CENTRAL BORE, SAID BORE INCLUDING A FIRST PORTION ADAPTED TO RECEIVE THE MUZZLE OF A SHOTGUN AND EXTEND FORWARDLY THEREFROM IN COAXIAL ALIGNMENT THEREWITH, SAID BORE INCLUDING A SECOND PORTION ADJACENT SAID FIRST PORTION, SAID BORE FURTHER INCLUDING A GENERALLY CYLINDRICAL THIRD PORTION ADJACENT SAID SECOND PORTION, SAID THIRD PORTION HAVING A DIAMETER SMALLER THAN THE SHOTGUN BORE DIAMETER, SAID SHELL DEFINING AT LEAST ONE VENT OPENING COMMUNICATING LATERALLY WITH SAID THIRD PORTION, AND MEANS FOR SELECTIVELY CLOSING AT LEAST A PORTION OF SAID VENT OPENING. 